Increasing evidence suggests that the eradication of minimal residual detectable disease is necessary for cure. Considerable effort has therefore been made over the past decade to develop sensitive methods to detect these minimal residual tumor cells in the patient. Polymerase chain reaction (PCR) amplification of non-random chromosome translocations permits sensitive detection of tumors. However, the majority of patients with multiple myeloma (MM) do not demonstrate such non-random chromosomal translocations, and alternative strategies are necessary to detect minimal residual disease (MRD). MM cells rearrange either the immunoglobulin (Ig) heavy or light chains or both, and their clonal progeny bear the identical rearrangement. This unique rearrangement provides a target for amplification and detection of MRD. Moreover, competitive PCR assays can be used to assess quantitatively the tumor burden within the patient. PCR analysis at both the Ig heavy and light chain loci will be used to amplify the MM specific antigen receptor. Sequence analysis of the PCR product will enable us to design junctional specific oligonucleotide probes to detect and quantitate leukemic burden in patients with MM undergoing novel treatment strategies. This core will provide the methodologies to test whether novel treatment strategies, outlined in Projects 1,2 and 3, are capable of eliminating detectable MM cells. Furthermore, since the Ig gene rearrangements are unique to the tumor cells, they provide a potential tumor antigen that can be used as a target for proposed immunotherapeutic strategies. To this end, we propose four specific aims. First: to PCR amplify and sequence Ig heavy and light chain rearrangement. Second, to design allele specific oligonucleotides derived from the I g sequences that can be used to detect and follow minimal residual disease in patients with MM. Third to clone and express the idiotype from patients with MM. Fourth to develop tools for the presentation of idiotype and other potential MM specific antigens for clinical trials. Our overall goal is to provide the techniques necessary to allow Projects 1,2 and 3 to assess the clinical significance of detection and quantification of MRD and hopefully to enable us to identify patients at high risk for subsequent failure. Furthermore, we can then assess whether any novel treatment approaches are capable of eradicating minimal disease in these patients, to address whether this can be used as a surrogate end-point predicting outcome in proposed clinical trials.